Color vision

“ The laws for this are founded on the peculiarity of the power of man's vision. The eye, demands to be satisfied, an accord of primary colors. Red requires to annihilate one sided irritation the two primary colors, yellow and blue. The secondary green is obtained by a combination of yellow and blue, for that reason green is the color demanded by red to please the eye. But there must be a contrast of colors, for instance light red and dark green or dark red and light green must be brought together. ”

“ The eye is quick to note the different hues that appear in the field of vision and readily selects five predominating colors, namely, gray, green, brown, purple and blue, which mingle harmoniously in various combinations with almost every other color that is known. ”

“ We must expect, then, in painting, to find that neutral gray will be more altered by pale tints of red, orange, or yellow, which are slightly lighter than itself, and that the gray will be less altered by these colors when differing considerably from it in luminosity; analogous conclusions with regard to green, blue, violet, and purple, can also be drawn. Saturated or intense colors in a painting have less effect on white or gray than colors that are pale; this was shown in the preliminary experiment when gray was placed on a ground of strong color. ”

“ Colors have their greatest importance for us in so far as they are properties of bodies and can serve as signs for the recognition of bodies.... We have become accustomed, in forming a judgment in regard to the colors of bodies, to eliminate the varying brightness and [Pg 18] color of the illumination. We have sufficient opportunity to investigate the same colors of objects in full sunshine, in the blue light of the clear sky, in the weak white light of a cloudy day, in the reddish-yellow light of the sinking sun or of the candle. ”

“ As a matter of fact, a highly trained eye can discover about a thousand different tints in the spectrum of white light. Time will not allow us to enter into any discussion of what is called colour-vision and the theory of sensations of colour. ”

“ Now, as the red nerves begin to be fatigued, the action of the other two sets will be relatively more powerful than at first, so that gradually the sensations of green and violet begin to add themselves to that of red, or, what is the same thing, the sensation of white mingles itself with that of red and makes the red color of the paper look a little grayish. The success of the experiment with the pure colors of the spectrum, which contain no white, is easily accounted for by the explanation just given. ”

“ We are all born color-blind. The most perfect eyes in the world cannot see one-quarter of the colors which are known to exist in nature. Those of us who are fortunate, it is true, are able to differentiate with reasonable exactness the three primary colors which go to make up our limited human color-scale—but what about the tones which certainly exist above the ultra-violet band and below the infra-red? ”

“ But we meet with slighter degrees of color-blindness, where the perception of red is not entirely wanting, but only considerably diminished; so that, for instance, an intense or strongly illuminated red can be perceived as such, while a less intense red appears green. This moderate degree of color-blindness does not always deter people from painting. A proof of this I saw at the last year's Exhibition, in a picture which represented a cattle-market. ”

“ The top figure is the red sensation on the Young theory; the middle is the green sensation, and the lowest the violet or blue sensation.
With the notion in our minds that the perceiving apparatus might act in the way that the pendulum acts, we naturally apply it to the theories which early investigators on colour vision propounded. ”

“ A normal vision under ordinary conditions, has no hesitation in correctly naming the sensations produced by the triad groups red, yellow and blue, or by the single rays orange, green and violet. It can also correctly describe a complex colour sensation, by naming the two associated colours, such as red orange, yellow orange, blue green, blue violet, etc. ”

“ If the visual sensation they possess be the violet, they will see no light at the extreme red of the spectrum, and very little in the orange. They must match every colour with some shade of grey, for they will only perceive that sensation, in what to ordinary normal eyes is white. We need not detail how those who possess monochromatic vision due to some other sensation would describe the different colours. The diagram will tell us. Suffice it to say, that one colour will only differ from another and from white in brightness. ”

“ In going to the solar spectrum for standards on which to base pigmentary standards, we have given little attention to these various theories in their details, but the one fact of science has received careful attention, namely, that all color effects in nature and art are produced by light reflected from material surfaces. ”

“ If we set the amount of light reflected by white paper as 100, then a surface painted with "emerald-green" reflects about eight parts of white light; artificial ultramarine, two or three parts; red lead, seven or eight, etc. Some white light is always present; its general effect is to soften the color and reduce its action on the eye; when the proportion of white is very large, only a faint reminiscence of the original hue remains; we say the tint is greenish-gray ”

“ White again is quite distinct from all the colours in the narrower sense of that word, and black, which we must accept as a sensation, as an affection of consciousness, even if we regard it as the absence of sensation from the field of vision, is again distinct from everything else.53 Hence the sensations caused by different kinds of light or by the absence of light, which thus appear to us quite distinct, and which we may speak of as ‘native’ or ‘fundamental’ sensations, are white, black, red, yellow, green, blue. ”

“ For the same reason grass is GREEN. The green waves of white light are thrown upon our eyes.”
“When we paint our houses, we do not apply color to them,” he said at another time. “What we do is to apply certain substances that have the property of absorbing from white light all the colors except those that we would have our houses appear. When a substance reflects all the colors to the eye, it seems to us white. When it absorbs all the colors, it is black. ”

“ People who are less refined admire deeper tones; yet want absolute harmony, while coarse individuals are satisfied with bright gaudy colors. Color is a sensation produced on the retina of the eye, by the action of one or more of the elements of light. Exact proportion by parts are not given in the following in order to let you be the judge of the exact shade. Follow the simple rule of using a little more of the dark colors of each color combination if a deeper shade is wanted and vice versa for a lighter one. ”

“ A red hat on a purple chair would set one's teeth on edge, in model or picture. Secondly, truth of color may be truth to the modifications of the enveloping light, and in this case truth would make for beauty. For the colors of any given scene are in general not colors which the objects themselves, if isolated, would have, but the colors which the eye itself is forced to see. The bluish shadow of an object in bright sunlight (yellowish light) is only an expression of the law that in the neighborhood of a colored object we see its complementary color. ”

“ It will help us to realize the nature of the defect to assume, which is not quite the case, that white light is composed of red, green, and violet in equal proportions and of equal luminosity; then to eyes which are incapable of seeing one of the colors, one third of the illumination of natural objects is extinguished, and the appearance the objects present is not that of their real color, but only of that fraction of their real color in which the two visible colors are combined in them. ”

“ Those valuable laws of optical illusion teach us always to select colors that have a tendency to recede, that is, those that are indefinite and difficult to classify. For instance, the moment rose is added to gray, or yellow to tan, it takes on light and tends to intensify size rather than to reduce it, while we can add white to gray, or brown to tan with the opposite result. So often we see someone who has achieved a beautiful color plan, change it to satisfy her own desire for variety and in the changing lose all that she has worked to gain. ”

“ In the case of simultaneous contrast, the changes are due mainly to fluctuations of the judgment of the observer, but little to the fatigue of the retinal nerves. We carry in ourselves no standard by which we can measure the saturation of color or its exact place in the chromatic circle; hence, if we have no undoubted external standard at hand with which to compare our colors, we are easily deceived. A slip of paper, of a pale but very decided blue-green hue, was placed on a sheet of paper of the same general tint, but somewhat darker and more intense or saturated in hue. ”

“ If it were not that colors can be compounded, we should be limited in hue and shade to the seven spectral colors; the wealth and beauty of color in nature, art, and commerce would be unknown; the flowers with their thousands of hues would have a poverty of color undreamed of; art would lose its magenta, its lilac, its olive, its lavender, and would have to work its wonders with the spectral colors alone. By compounding various colors in different proportions, new colors can be formed to give freshness and variety. ”

“ To determine the hue of a pigment from the analysis of the light it reflects is a problem in physiological optics, the solution of which varies with the character of the observer's eye. The three primary color-curves of the eye must be determined, and the total intensity of each wave-length of the spectrum of the pigment must be divided in the proportions indicated by the color-curves into three components—red, green, and violet. ”

“ When the eye has been fatigued by looking intently for a few seconds at a red spot on a white wall and is then slightly turned to the wall, a faint tint of a bluish green is seen, and this is called the accidental color of the red, and is supposed to be identical with its complementary color. If with the disks we determine a color which with a given color will produce by rotation a neutral gray, we have the complementary color more accurately than by any other means at present known in the use of pigmentary colors. ”

“ It is, however, more congenial with yellow than with blue, and thence partakes more of the character of the former in its effects of warmth, the influence of light and distance, and action on the eye, by which the power of vision is diminished on viewing this colour in a strong light. On the other hand, red appears to deepen in colour rapidly in a declining light as night comes on, or in shade. These qualities of red give it great importance, render it difficult of management, and require it to be generally kept subordinate in painting. ”

“ In consequence of this law of contrast of tone the contrast of black with active colors generally tends to intensify the black and lower the tone of the color, i.e., to weaken it as though white or light gray was mixed with it, but this effect is modified by contrast of color. ”

“ As an artist's color, it replaces almost all the other red pigments which we have inherited from the past. The same chemists have an equally powerful yellow and blue under careful observation, and it is highly probable that in another year or two these, also, will be given to the world. Now it is evident that if painters can secure these three primary colors in two values, a light and a dark shade, they will, with the addition of white and black, have a perfect palette ”

“ We then shall have representations of all the spectrum colors, but there are still the colors between violet and red, known in nature and art as purples, which must be produced by uniting the red and violet disks, thus completing a circuit of colors containing all the pure colors in nature.
In nature all colors are modified by light and shade, strong light producing tints and shadows more or less deep forming shades. ”

“ For what I may call the straightforward part of190 colour vision, dealing with ordinarily bright colours, the Young theory is amply sufficient; but when we come to the feeble luminosities and the colour fields, it is again difficult to adapt to explain the phenomena observed. When we reduce the luminosity of a coloured ray sufficiently we feel the sensation of grey light: no colour is felt. ”

“ Experiments of this kind are particularly difficult, inasmuch as the material, usually colored paper, varies considerably from the spectral color, and differences in saturation, hue, and brightness make great differences in the results, while the feeling-tone of association, individual or racial, very often intrudes. But other things being equal, the bright, the clear, the saturated color is relatively more pleasing, and white, red, and yellow seem especially preferred. ”

“ All the recent scientific writers on color treat this three-color scheme as already exploded, because the simplest as well as the most complex experiments with colored light prove its falsity. Nevertheless, the fact that yellow and blue, which with light make very nearly white, do in the mixture of pigments produce a green, has deceived many persons. ”

“ The question of the demands of the eye in color combination is still more complicated. It has been traditional to consider the complementaries black-white, red-green, blue-yellow, and the other pairs resulting from the mixtures of these as the best combinations. The physiological explanation is of course found in the relief and refreshment to the organs in successive alternation of the processes of assimilation and dissimilation, and objectively in the reinforcement, through this stronger functioning of the retina, of the complementary colors themselves. ”